The Orion Nebula Cluster

This image shows a ROSAT HRI-observation of the Orion nebula region
(data taken from the ROSAT data archive; see Gagne et al. 1995, ApJ 445, 280
for a detailed analysis). The field of view is
about 40 x 40 arcmin, centered on the Trapezium.
The very strong source near the upper edge is the star P1724.
This star showed a giant X-ray flare during the ROSAT observation,
probably the most energetic X-ray flare ever observed.
(For details see the
abstract of our A&A
paper on this flare).